Belt-type presses for making particleboard, fiberboard, and the like known in the prior art related to our invention generally comprise an endless upper press belt, preferably a steel press belt, circulated over at least one upper belt guide roller, a corresponding endless lower press belt, preferably a steel press belt, circulated over at least one lower belt guide roller, these press belts forming a pressing gap in a pressing region of the belt-type press, and a press framework having a lower and an upper platen as well as a drive mechanism. In the pressing region between each of the platens and its corresponding press belt a rod supply is positioned in which a plurality of rolling rods are fed with spacing from each other, and are guided over a circulation path with the aid of either an upper or lower rod circulation mechanism.
Each rod circulating mechanism comprises two first or main chains each guided over at least one sprocket and at least one first chain drive wheel, a plurality of interlocked chain link members having chain bolts attached therein, a plurality of outer running rollers mounted on the chain bolts, and at least one guide rail for the running rollers, the rolling rods being attached between the two first chains with equalizing free play.
At least one end of each of the rolling rods has a recess bored therein, in which each one of a plurality of support rods attached to the first chains engage so as to provide the equalizing free play.
At an entrance region of the pressing gap and of the platens a second chain, comprising a plurality of chain rollers in a triangular configuration guided over at least one second chain guide wheel, is positioned, over the chain rollers of which the rolling rods between the first chains are guided as with roller bearings.
The press products can include also laminates, rubber products, plastics and the like.
In the belt-type presses of the prior art, as taught in German patent document DE-OS No. 31 19 529 (see also U.S. Pat. No. 4,480,978, No. 4,457,683 and No. 4,468,188), the upper and lower guide mechanism has two first chains guided in synchronization over first chain guide wheels or sprockets whose link members are forced together in a zig-zag shape in the pressing region, whereby an equalizing free play originates.
The rolling rods are attached to the articulations or pivot joints of the adjacent link members at the press belt side of the first chains, and running rollers are supported on the pivot joints or articulations on the press platen side of the first chain.
The first chain extending in the return path behind the pressing region and the draw chain for the rolling rods are guided back over the sprocket to the entrance mechanism. The entrance mechanism comprises a driven sprocket and a sliding wheel cooperating with it with connected guide bars for at least the running rollers.
The guide bars guide the rolling rods until they reach the entrance of the pressing region. In this way the rolling rods do not undergo guiding force in the pressing region. This known press embodiment uses the fact, that the rolling rods run undisturbed in the pressing region, when they are formed in an adequate cylindrical form, and that care must be taken that they are input exactly perpendicular to the circulating direction.
The known presses which have proved to be good, demand however that the first chains, which are collapsed or forced together in a zig-zag shape, and the corresponding steps for the sliding together, be used.
Moreover practice demands particularly with very long condinuously operable presses, an extremely precise input of the rolling rods, and of course with narrow tolerances required, perpendicularly to the circulating direction of the rolling rods. But the prior art presses of this type can be improved. Usually the known belt-type presses of this kind are additionally provided at the entrance end of the press with an inlet press, which has a plurality of circulating second chains or press bands, which are distributed with clearance from each other over the width of the press belts, wherein the rolling rods are supported in the entrance region on the chain rollers of the second chains.